1. Field of the Invention
The present invention relates to the technical field of contactless detection or measurement, respectively, of three-dimensional objects. In particular, the present invention relates to the technical sub-field of scanners for detecting a surface relief by means of optical scanning.
2. Description of Prior Art
Known scanners for short object distances mainly use the method of triangulation, as it is illustrated in FIG. 7. Here, from a light source 705 of a scanner 700 a suitable light pattern is protected onto the object 710 to be examined, while an electronic image receiver 720 detects the resulting image from a different angle of view. As it is illustrated in FIG. 7, the surface profile of the object 710 that may be twisted or shifted, respectively, in different directions 730 and 740, leads to an offset of the projected light pattern with regard to a reference level 750, from which object coordinates may be calculated via image processing algorithms. A complete spatial module of the object 710 may be obtained when the object 710 and the scanner 700 are moved in a defined way relatively to each other. FIG. 7 thus shows a 3D scanner operating according to the triangulation principle. Depending on the application, different light sources are used, like for example traditional projectors having shadow masks for structuring (e.g. DE 000010149750 A1, US 00006501554 B1) or laser light sources corresponding for example to DE 000019721688 A1. Also light sources having attachment optics for generating light figures according to DE 000019615685 A1 or ones having DMD members (DMD=Digital Micro Device) may be used for generating electronically controllable light figures, for example according to EP 000000927334 B1, US 000006611343 B1, DE 000019810495 A1. Any known devices of those classes use laminar (DE 000010149750 A1 or DE 000019615685 A1) or at least line-shaped image sensors (at it is for example disclosed in US 000006501554 B1) as image receivers, however, on the basis of CCD or CMOS technology (CCD=Charge Coupled Device=sensor type that accumulates electrical charges under light incidence that are fed to suitably controlled electrodes of a read-out electronic; CMOS=Complementary Metal Oxide Semiconductor=widely used circuit technology and manufacturing technology for integrated solid circuitries on a silicon basis).
Recently, with the so-called micro scanner mirrors new elastically suspended micro optical members electro-statically excited close to their natural resonance and the associated control electronics are available, as it is for example explained in more detail in the following documents:
A New Driving Principle for Micromechanical Torsional Actuators
H. Schenk, P. Dürr, D. Kunze, H. Kück; Micro-Electro-Mechanical System, MEMS-Vol. 1, Conf.: 1999 int. Mech. Eng. Congr. & Exh., 14-19 Nov. 1999, Nashville, p. 333-338, 1999
A Novel Electrostatically Driven Torsional Actuator
H. Schenk, P. Dürr, H. Kück Proc. 3rd Int. Conf. On Micro Opto Electro Mechanical Systems, Mainz, 30. Aug.-1. Sep. 1999, page 3-10, 1999
Micromirror Spatial Light Modulators
P. Dürr, A. Gehner, U. Dauderstädt, 3rd International Conference on Micro Opto Electro Mechanical Systems (Optical MEMS) Proc. MEMS 1999, Mainz, 1999, S. 60-65
A Resonantly Excited 2D-Micro-Scanning-Mirror with Large Deflection
H. Schenk, P. Dürr, D. Kunze, H. Lakner, H. Kück Sensors & Actuators, 2001 Sensors & Actuators, A 89 (2001), Nr. 1-2, ISSN 0924-4247, S. 104-111
Large Deflection Micromechanical Scanning Mirrors for Linear Scans and Pattern Generation
H. Schenk, P. Dürr, T. Haase, D. Kunze, U. Sobe, H. Lakner, H. Kück Journal of Selected Topics of Quantum Electronics 6, (2000), Nr. 5 ISSN 1077-260X, S. 715-722
An Electrostatically Excited 2D-Micro-Scanning-Mirror with an In-Plane Configuration of the Driving Electrodes
H. Schenk, P. Dürr, D. Kunze, H. Lakner, H. Kück Proc. MEMS 2000, 13th Int. Micro Electro Mechanical Systems Conf, Miyazaki, Japan, page 473-478, 2000
Mechanical and Electrical Failures and Reliability of Micro Scanning Mirrors
E. Gaumont, A. Wolter, H. Schenk, G. Georgelin, M. Schmoger 9th Int. Symposium on the physical and failure analysis of integrated circuits (IPFA 9), 8-12 Jul. 2002, raffles City Convention Centre, Singapore, Proc. New York, IEEE Press, 2002, ISBN 0-7803-7416-9, S. 212-217
Improved Layout for a Resonant 2D Micro Scanning Mirror with Low Operation Voltages
A. Wolter, H. Schenk, E. Gaumont, H. Lakner, SPIE Conference on MOEMS Display and Imaging Systems (mf07), 28-29 Jan. 2003, San Jose, Calif., USA, Proceedings, Bellingham, Wash.: SPIE, 2003 (SPIE Proceedings Series 4985) ISBN 0-8194-4785-4, S. 72-74
US020040183149A1
Micromechanical device
WO002003010545A1
Mikromechanisches Bauelement (Micro-mechanical device)
WO002000025170A1, Mikromechanisches Bauelement Mit Schwingkorper (Micro-mechanical Device With Vibrating Body) EP000001123526B1, US000006595055B1
WO002004092745A1
Mikromechanisches Bauelement Mit Einstellbarer Resonanzfrequenz (Micro-mechanical Device With Settable Resonance Frequency)
Driver ASIC for Synchronized Excitation of Resonant Micro-Mirror
K.-U. Roscher, U. Fakesch, H. Schenk, H. Lakner, D. Schlebusch, SPIE Confernece on MOEMS Display and Imaging Systems (mf07), 28-29 Jan. 2003, San Jose, Calif., USA, Proceedings, Bellingham, Wash.: SPIE, 2003 (SPIE Proceedings Series 4985) ISBN 0-8194-4785-4, S. 121-130
The class of MOEMS (MOEMS=Micro Opto Electromechanical Systems) allow to deflect light beams in an electronically controlled way one- or two-dimensional so that using points-shaped light sources or detector elements, respectively, an area or a solid angle may sequentially be scanned or sweeped (scanning).
For projection purposes the use of resonant micro-mirrors already represents a known solution, which may for example be seen from the following documents:
DE 000019615685 A1
Low Cost Projection Device with a 2-Dimensional Resonant Micro Scanning Mirror
K.-U. Roscher, H. Grätz, H. Schenk, A. Wolter, H. Lakner MEMS/MOEMS display and imaging systems II (2004), pp. 22-31
WO002003032046A1, Projektionsvorrichtung US020040218155A1,
Also the projection purposes mirrors are used in another way, for example moved in a rotating way according to DE 000010304187A1, DE000010304188A1 and WO002004068211A1 or be already mentioned DMD members according to EP 000000927334B1, US00000661134B1 or DE 000019810495A1 for generating light patterns.
One possibility for a one-dimensional detection of a position of a light beam was presented in “Torsional stress, fatigue and fracture strength in silicon hinges of a micro scanning mirror” of A. Wolter, H. Schenk, H. Korth and H. Lackner (SPIE Bellingham Wash. 2004; Proceedings of SPIE Vol. 5343). This one-dimensional detection of a position of a light beam only offers a coarse and delayed possibility for a determination of the position of the light beam, as the described method requires a complete pass of the light beam between two oscillation amplitude maxima of a travel path of the light beam.
Further, for the application area of the following invention, still the further documents are relevant:
EP000000999429A1 Messinstrument für 3D Form mit Laser Scanner und Digitalkamera (Measurement Instrument for 3D-form with laser scanner and digital camera
US020030202691A1 Calibration of multiple cameras for a turntable-based 3D scanner
US000006486963B1 Precision 3D scanner base and method for measuring manufactured parts
DE000019846145A1 Verfahren und Anordnung zur 3D-Aufnahme (Method and Arrangement for 3D-Recording)
DE000019613978A1 Verfahren zum Zusammenfügen der Messdaten unterschiedlicher Ansichten und Objektbereiche bei der optischen 3D-Koordinatenmeβtechnik mittels flächenhaft und auf der Basis von Musterprojekten arbeitenden Triangulationssensoren (Method for joining the measurement data of different views and object areas in the optical 3D-coordinate measurement technology by means of triangulation sensors operating in a laminar way and on the basis of sample projection)
DE000019536287A1 Verfahren zur geometrischen Kalibrierung von optischen 3D-Sensoren zur dreidimensionalen Vermessung von Objekten und Vorrichtung hierzu (Method for a geometric calibration of optical 3D sensors for a 3-dimensional measurement of objects and devices for the same)
DE000019536294A1 Verfahren zur geometrischen Navigation von optischen 3D-Sensoren zum dreidimensionalen Vermessen von Objekten (Method for a geomectrical navigation of optical 3D sensors for a 3-dimensional measurement of objects)
EP000001371969A1 Ausrichtungsverfahren zum Positionieren von Sensoren für 3D-Meβsysteme (Alignment method for positioning sensors for 3D measurement systems)
WO002000077471A1 Vorrichtung zur Berührungslosen Dreidimensionalen Vermessung von Körpern und Verfahren zur Bestimmung eines Koordinatensystems für Messpunktkoordinaten (Device for a contactless 3-dimensional measurement of bodies and methods for determining a coordinate system for measurement point coordinates)
EP000000916071B1 Triangulation-Based 3D Imaging And Processing Method And System
US000005546189A Triangulation-based 3D imaging and processing method and system
US000005654800A Triangulation-based 3D imaging and processing method and system
WO001998005923A1 Triangulation-Based 3D Imaging And Processing Method And System
CA000002365323A1 Method Of Measuring 3D Object And Rendering 3D Object Acquired By A Scanner
DE000019721903C1 Verfahren und Anlage zur meβtechnischen räumlichen 3D-Lageerfassung von Oberflächenpunkten (Method and apparatus for a measurement-technical spatial 3D position detection of surface points)
CA000002376103A1 Active Structural Scanner For Scanning In 3D Mode Data Of Unknown Structures
However, all these prior-art approaches are of disadvantage in that they require either an area camera or at least a line camera for detecting the image reflected by the object or may only detect a position of the image by means of a complicated control of micro mirrors having micromechanical electric motors in order to detect the three-dimensional surface relief therefrom. In addition, the solution of the complicated control of the micro mirrors has the additional disadvantage that this control is mechanically sensitive, area-consuming and, additionally, expensive. Also, using an area or line camera requires considerable space and is also expensive.